The present invention is a process for the preparation of hydrolyzable .beta.-cyanoalkylsilanes. More particularly, this invention relates to the catalytic addition of silicon hydrides to .alpha.,.beta.-unsaturated olefinic nitriles to form .beta.-cyanoalkylsilanes. The instant process employs a catalyst mixture comprising a diamine and supported copper or a supported copper compound.
Hydrolyzable .beta.-cyanoalkylsilanes are useful for the production of polyorganosiloxanes containing the .beta.-cyanoalkyl substituent. The silicon-bonded .beta.-cyanoalkyl radical is extremely resistant to hydrolysis and cleavage under hot, humid conditions. Therefore, the .beta.-cyanoalkylsilanes find particular use in the preparation of polyorganosiloxanes which must be subjected to hot humid conditions. The presence of the silicon-bonded .beta.-cyanoalkyl radical substituted on polyorganosiloxanes also tends to stabilize the polyorganosiloxanes against swelling induced by liquid hydrocarbons.
Bluestein, U.S. Pat. No. 2,971,970, issued Feb. 14, 1961, describes a method for forming cyanoalkylsilanes. The method comprises reacting a hydrolyzable silicon hydride with an .alpha.,.beta.-unsaturated olefinic nitrile in the presence of a diamine and a cuprous compound selected from the class consisting of cuprous oxide and cuprous halides.
Rajkumar et al., Organometallics 8. 550-552. 1989, describes a two-component catalyst, consisting of cuprous oxide and tetramethylethylenediamine, that promotes .beta.-hydrosilylation of acrylonitrile.
Svoboda et al., Collection Czechoslov. Chem. Commun. 38, 3834-3836, 1973, describes binary systems of a copper compound (Cu(I) oxide. Cu(I) chloride, or Cu(II) acetylacetonate) and an isocyanide (tert-butyl or cyclohexyl isocyanide) as effective catalysts for hydrosilylation of acrylonitrile by trichlorosilane and methyldichlorosilane.
The present process employs a catalyst, comprising a diamine and supported copper or a supported compound of copper, which promotes the .beta.-hydrosilylation of unsaturated olefinic nitriles by silicon hydrides. The use of supported copper or a supported copper compound as a component of the catalyst permits retention of the supported copper component in continuous processes and easy recovery and reuse of the supported copper component in batch type processes.